The invention is concerned with methods for in vivo immunotherapy of cancers associated with production of human chorionic gonadotropin (hCG) by administering a human anti-hCG monoclonal antibody and/or an hCG immunogenic peptide vaccine. The invention further relates to methods and devices for monitoring and adjusting the treatment regimen of patients, based on the results of an evaluation of the immune response to the 37 mer C-terminal fragment of hCG (hCG-CTP37) and immunogenic fragments thereof.
References
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Vaccination is a means for preparing the immune system to reduce disease symptoms, prevent horizontal transmission of infectious agents and reduce disease mortality. It is well known that the immune system of a subject will generate an immune response to foreign antigens. It is also known to confer immunity on an animal by administering an antibody formed elsewhere (i.e. passive immunization).
Standard vaccines include the administration of carbohydrates, peptides, polypeptides, and glycosylated polypeptides against which an immune response is desired (active immunization). Alternatives to vaccine administration include the administration of pre-formed antibodies to one or more peptide or polypeptides (passive immunization). Although polyclonal and monoclonal antibodies are readily produced by routine techniques, until recently, production and purification of safe antibody compositions has been relatively expensive and time consuming.
Historically, there have been serious limitations to the use of passive immunization procedures for human therapy. These limitations are most evident in the treatment of chronic diseases such as cancer due to the cost of antibody production and the requirement for prolonged administration of these antibodies. Additional difficulties are encountered when the immunogen is a soluble protein or an endogenous protein not normally recognized by the immune system of the subject.
Certain cancers are highly resistant to attack by the immune system of a host, even though in theory the host should mount an immune response against the cancer. It is believed that this resistance is due to the ability of the cancer to interfere with the normal immune response to the cancer cells, thereby allowing them to grow and proliferate.
Normally, Chorionic gonadotropin (CG), e.g. human chorionic gonadotropin (hCG), is secreted by cells of the human placenta and blastocyst. However, many human cancers produce and retain and/or secrete hCG at some point during carcinogenesis. hCG has been detected in the membranes of a variety of human cancer cell lines (Acevedo, et al., 1992), and in the serum of cancer patients (Braunstein, 1990). In fact, the hCG beta subunit C-terminal peptide (CTP) is highly expressed by a variety of cancers, and immunization with this construct has demonstrated antitumor activity in preclinical studies (Acevedo, et al., 1992; Acevedo, et al., 1987)).
For example, it has been demonstrated that hCG and/or its subunits are made by human lung cancer cells and that the hCG polypeptide or portions of it act as autocrine growth promoters for the tumor cells. (See, e.g., Rivera et al., 1989.) Additional references also describe that the active production of anti-hCG antibodies in tumor-bearing animals can result from administration of an hCG vaccine. (See, e.g., U.S. Pat. Nos. 5,762,931 and 4,780,312.).
Several biological activities associated with the ability of cancer cells to proliferate have been attributed to hCG including; (1) a link to tumor anergy (the lack of the immune response to tumors), (2) enhancement of tumor blood supply, and (3) the observation that hCG acts as a growth stimulatory factor for many cancer cells.
Epidemiological surveys indicate that human lung cancers are often associated with synthesis of hormones, predominantly human chorionic gonadotropin (hCG). Increased circulating levels of hCG and its subunits are often used as biochemical markers for malignancy, and decreased levels of hCG used as markers for successful surgery in human lung tumors. Free and/or tumor-associated xcex2-hCG has been detected in bladder, pancreatic, cervical, colorectal, lung, pancreatic, esophageal breast, gastric, prostate, ovarian, uterine, cervical, and endometrial cancers, in addition to a majority of patients with germ cell tumors. (See, e.g., Dirnhofer, et al., 1998; Triozzi P L and Stevens V C, 1999). hCG and other gonadotropic hormones have also been associated with Kaposi""s Sarcoma (K S, Fife, K and Bower, M, 1996).
Colorectal cancer is a disease that kills nearly half of those afflicted within 5 years of initial diagnosis and approximately one in 17 Americans develop colorectal cancer during their lifetime. Surgical intervention is not an option for most patients with advanced metastatic colorectal cancer. Initial chemotherapy with fluorouracil (5-FU) and leucovorin has become the standard for patients with stage III colon cancer (NIH Consensus Conference. Adjuvant therapy for patients with colon and rectal cancer. JAMA 264: 1444-1450, 1990; Goldberg R M and Erlichman C. Oncology 12: 59-63, 1998). Therapy for patients with 5-FU-refractory advanced colorectal cancer is currently irinotecan (Van Cutsem E and Blijham G H. Semin Oncol 26:. 13-20, 1999 and Cunningham D et al. Lancet 352: 1413-1418, 1998). Multiple new approaches to the treatment of advanced colorectal cancer include: (a) new drugs such as oxaplatin, capecitabine, uracil/tegafur (UFT), (Punt C J., Cancer 1998; 15: 679-689, 1998); (b) passive immunotherapy using a monoclonal antibody, 17-1A (Punt C J., 1998); and (c) several approaches to active specific immunotherapy (ASI) with one or more cancer-associated antigens (Goydos J S et al. J Sur Res 1996; 63: 298-304 and Vermorken, J B et al. Lancet 1999; 353: 345-350).
Several Ohio State patents to Stevens, e.g., U.S. Pat. Nos. 4,767,842, 4,855,285, 5,817,753 and 5,698,201, expressly incorporated by reference herein, disclose the use of a beta-hCG/tetanus toxoid modified peptide as an anti-cancer strategy based on antibody production against hCG by the host.
Although various research efforts are directed to improved methods for treatment of hCG-expressing cancers, there remains a need for an effective and safe method for reducing or eliminating the level of circulating CG and cell-associated CG in cancer patients with CG-expressing tumors.
It is therefore a general object of the invention to provide methods for immunotherapy of cancers which express human chorionic gonadotropin (hCG), or an immunogenic epitope thereof.
The invention relates to methods of eliciting an immune response against hCG by administering an hCG immunogenic peptide vaccine composition to a subject, particularly a human cancer patient, as a means to diminish, prevent the spread of, and/or progression of cancer.
The invention also relates to a human monoclonal antibody composition specifically immunoreactive with a 21 mer N-terminal fragment of hCG-CTP37 (hCG-CTP21, SEQ ID NO:4) alone, or in combination with a human monoclonal antibody specifically immunoreactive with a 16 mer C-terminal fragment of hCG-CTP37 (hCG-CTP16, SEQ ID NO:6).
Such human monoclonal antibody compositions may be prepared in a solution suitable for injection in a human patient and find utility in passive immunotherapy, particularly immunotherapy of cancer.
In one aspect, the invention provides a method for immunotherapy of cancer by administering a human monoclonal antibody composition 1 to 2 times per week for a period of at least 4 to 6 weeks, at dose of from about 25 to 500 mg.
In a related aspect, a human monoclonal antibody composition is administered together or sequentially with an hCG immunogenic peptide vaccine, derivatized to a suitable carrier protein. In one approach, the peptide vaccine is hCG-CTP37 (SEQ ID NO:2), alone or in combination with the hCG xe2x80x9cloopxe2x80x9d peptide (SEQ ID NO:9).
In another embodiment, the invention provides a method for classifying the immune response to hCG in a patient, by measuring the levels of patient anti-hCG antibodies specific to hCG-CTP16 (SEQ ID NO:6), hCG-CTP21 (SEQ ID NO:4), and hCG-CTP37 (SEQ ID NO:2), respectively, and classifying the patient into one of the following four groups, depending on the relative antibody levels, as follows, (1) patients in which neither anti-CTP16 nor anti-CTP21 antibodies, nor total anti-hCG-CTP37 antibodies are detectable (non-antibody responders); (2) patients in which in which total anti-hCG-CTP37 antibodies are detectable while neither first nor second antibodies are detectable (poor antibody responders); (3) patients having a detectable level of first antibodies, but undetectable levels of second antibodies (CTP16 only antibody responders); and (4) patients having detectable levels of both first and second antibodies (CTP16 and CTP21 antibody responders).
The invention further provides an improved method of treating a cancer patient population that fails to respond to an hCG-CTP37 vaccine dose of at least 1 mg peptide per administration, as evidenced by a negligible improvement in the patient""s condition. The assay is typically carried out between 9-15 weeks after an initial vaccination, and if the patient""s measured level of anti-hCG-CTP21 antibodies is undetectable or substantially lower than that of anti-hCG-CTP16 antibodies, further treating the patient by a vaccination regimen selected from one or more of: (i) successive, spaced administrations of hCG-CTP37 at a dose which is greater than that provided in the initial administration; (ii) successive, spaced administrations of hCG-CTP37 at a dose corresponding to less than 1 mg CTP37 peptide/patient/administration; (iii) successive, spaced administrations of a promoter vaccine composed of hCG loop peptide (SEQ ID NO:9) derivatized to a suitable carrier, in combination with the hCG-CTP37 (SEQ ID NO:2) vaccine; (iv) successive, spaced administrations of a promoter vaccine composed of hCG loop peptide (SEQ ID NO:9) derivative to a suitable carrier, followed by successive spaced administrations of the hCG-CTP37 (SEQ ID NO:2) vaccine, at a dose of the latter vaccine of less than less than 1 mg CTP37 peptide/patient/administration; (v) successive spaced administration of a CTP37 N-terminal peptide vaccine composed of hCG-CTP21 (SEQ ID NO:4), derivatized to a suitable carrier protein; (vi) successive, spaced administrations of a human monoclonal antibody specifically immunoreactive with hCG-CTP21 (SEQ ID NO:4) at least once every 1 to 2 weeks; (vii) successive, spaced administrations of a human monoclonal antibody specifically immunorcactive with hCG-CTP21 (SEQ ID NO:4) together with a human monoclonal antibody specifically immunoreactive with hCG-CTP16 (SEQ ID NO:6), at least once every 1 to 2 weeks; and (viii) successive spaced administrations of an hCG-CTP37 vaccine in combination with a human monoclonal antibody specifically immunoreactive with hCG-CTP21 (SEQ ID NO:4).
In a related aspect of this embodiment, the invention provides a diagnostic device and method for monitoring the immune response to hCG, which includes an hCG-CTP16 peptide, an hCG-CTP21 peptide, and an hCG-CTP37 peptide together with a reagent means for labeling human antibodies that are immunoreactive with the peptides and a detectable reporter.
These and other objects and features of the invention will be more fully appreciated when the following detailed description of the invention is read in conjunction with the accompanying drawings.